What is the value of the International Date Line (IDL) in degrees?

The International Date Line is located at 180 degrees longitude. It serves as the boundary for calendar days, providing a point where the date changes when crossing from one side to the other. Specifically, when you cross the IDL traveling eastward, you subtract a day, while traveling westward adds a day.

Understanding the significance of the IDL helps clarify its function in the global coordinate system and the way we mark time across different regions of the world. The IDL is not a perfect straight line; it zigzags around political and geographical boundaries to ensure that entire countries remain within the same date. This consideration reinforces its importance in both navigation and international relations.